1. Field of the Invention
The present invention relates to composite materials and methods for fabricating the same and, particularly, to a magnesium-based composite material and a method for fabricating the same.
2. Discussion of Related Art
Nowadays, various alloys have been developed for special applications. Among these alloys, magnesium alloys have relatively superior mechanical properties, such as low density, good wear resistance, and high elastic modulus. Generally, two kinds of magnesium alloys have been developed: casting magnesium alloy and wrought magnesium alloy. In wrought magnesium alloy, by using an extrusion process, most of the casting defects can be eliminated and the metal grains can be refined. However, the toughness and the strength of the magnesium alloys are not able to meet the increasing needs of the automotive and aerospace industry for tougher and stronger alloys.
To address the above-described problems, magnesium-based composite materials have been developed. In the magnesium-based composite material, nanoscale reinforcements are mixed with the magnesium metal or alloy. The most common methods for making the magnesium-based composite material are through powder metallurgy and stir casting. However, in powder metallurgy, the metal or alloy is easily oxidized because the metal or alloy is in the form of a fine powder. In particular, the magnesium powder may spontaneously combust due to oxidization. In stir casting, the nanoscale reinforcements are added to melted metal or alloy and are prone to aggregate. As such, the nanoscale reinforcements can't be well dispersed. Further, the above-mentioned methods generally include complex processes using high cost manufacturing equipment.
What is needed, therefore, is to provide a magnesium-based composite material and a method for fabricating the same, in which the above problems are eliminated or at least alleviated.